If you want something done, sometimes you just have to do it yourself.

The city and county of San Francisco teamed up with Earthlink and Google nearly a decade ago to build what was planned as a citywide Wi-Fi network, only to see Earthlink retreat from its municipal Wi-Fi business in 2007. The citywide system was never built.

Now San Francisco is taking another shot at that goal and is going it alone, at least for now. On Monday, the city will turn on free outdoor Wi-Fi along Market Street, the city's main drag, all the way from the central Castro District to where the street meets San Francisco Bay. On Monday morning, a splash screen appearing on the network read, "Welcome! Enjoy This Free Service. Mayor Edwin M. Lee."

The network will be free, won't carry ads and won't require users to sign in. Unlike the failed Earthlink system, it won't be offered as a home broadband service and will be strictly an outdoor network.

San Francisco, Philadelphia, a group of Silicon Valley governments and other municipalities placed high hopes on public-private Wi-Fi networks in the middle of the last decade as a way to make public areas more attractive to Internet-savvy visitors and get underserved, low-income people online. But proposed business models built around advertising or daily and monthly largely subscriptions proved unsuccessful and in some cases were legally challenged by private service providers. Since then, some networks centered more on municipal uses and resources have emerged.

After the disappointments of the past, and drawn-out discussions of possible new projects since Earthlink pulled out, the Market Street deployment will prove city Wi-Fi can work in San Francisco, said Marc Touitou, the city's CIO.

"The citizens are going to say, OK, those guys are for real. They can do this," said Touitou, who was hired earlier this year. Planned as a three-month project, the Market deployment missed that target but was completed in a matter of months, in contrast to the years of wrangling involved in the Google-Earthlink network.

"I believe that I can go much faster just with the agencies of the city," Touitou said.

The city is getting some help from Wi-Fi vendor Ruckus Wireless, though not of the type Earthlink and Google offered the last time around. Ruckus simply donated more than 150 of its ZoneFlex 7782-S outdoor access points, along with network controllers, and helped the city install them and link them to its 130-mile municipal fiber backbone. Where fiber isn't available, the access points can mesh with each other. The Wi-Fi gear is mounted on the city's own assets, such as traffic light poles, so San Francisco didn't have to lease space on private buildings.

The open network, with the SSID "_San Francisco_Free_WiFi," won't require any sign-on information from users. Like many of the tech startups surfacing around San Francisco these days, the city has no revenue model for its would-be disruptive technology. It simply wants to take the lead in deploying a type of service that Touitou thinks will be ubiquitous in all cities eventually.

The Market Street network by itself is no small thing. Stretching about three miles along the multilane thoroughfare, it is designed to provide an average of at least 2Mbps downstream and 1Mbps upstream throughout, with peak speeds as high as 50Mbps downstream depending on the number of users in the area. The city deployed the Ruckus ZoneFlex 7782-S outdoor access points on its own assets, such as traffic light poles, at an out-of-pocket cost of about US$500,000.

"Why Market Street? It's a gold corridor," Touitou said. The street bisects the eastern half of the city and is a major corridor for transit, as well as hosting numerous outdoor seating areas. The so-called Mid-Market area is home to Twitter's new headquarters and the focus of a major city rejuvenation project aimed at tech startups. On busy parts of Market Street, pedestrians frequently pass each other on the sidewalk with their eyes glued to smartphones and tablets.

If the current project was quick and relatively inexpensive, the citywide network it's supposed to set in motion will take much more money and organization. Still, the city plans to keep leveraging its own assets and own any future network that's built out.

The key to making a wider network happen may be service providers' growing need for capacity in areas packed with people using mobile devices, Touitou said. Though much of the city is well covered by cellular networks, mobile operators are looking for ways to offload traffic from their own frequencies to public Wi-Fi networks running on unlicensed spectrum, he said.

The promise of a citywide offload network might entice one or more mobile operators to either fund the wider rollout or pay the city for access to its capacity over time, Touitou said. The system would be open to any service provider, including carriers, cable operators and independent local competitors, he said.

That reflects one of the lessons learned from San Francisco's earlier flirtation with citywide Wi-Fi, said Ron Vinson, the chief marketing officer of the city's department of technology. Critics called the Earthlink-Google project a city giveaway to favored corporations. The absence of sign-in requirements should help to ease other past concerns about user privacy, he said.

The city might also look for sponsors to lend their brands to the network, Touitou said. The citywide system might be advertised as "powered by" a certain entity, but that sponsor wouldn't necessarily be involved in the network or service, he said.

San Francisco's Wi-Fi evangelists still have social motivations in mind. Since the days of the Earthlink-Google project, the city has operated free Wi-Fi for broadband service in public housing projects, Vinson said. Another project, funded through a donation from Google, is intended to light up the city's parks.

Touitou sees connectivity as a basic right of citizens. But there are dollars and cents involved, too. Increased broadband penetration has been shown to increase countries' gross domestic products, Touitou said. "If you don't take action to increase the broadband penetration, it's counterproductive to our economic development."